The present invention relates to an interlock valve which operates when a fluid pressure signal is input to any one of a plurality of input ports to select a flow path for working fluid.
For example, an interlock valve device is used for controlling pressure fluid such as compressed air and pressure oil supplied to a fluid pressure apparatus or for controlling fluid such as gas and liquid supplied to chemical machines and instruments for reactions, measurements, and the like. The valve device is normally formed of one pilot-type selector valve and an OR circuit which is a combination of a plurality of shuttle valves. If a fluid pressure signal is input to any one of a plurality of input ports communicating with the OR circuit, pilot fluid is output from the OR circuit to the selector valve and the selector valve operates to select a flow path for working fluid.
In such a valve device, the selector valve and the plurality of shuttle valves are normally mounted onto a manifold. In this case, if the selector valve and the shuttle valves are formed individually, they are badly organized as a whole and difficult to handle, it requires much trouble to mount them onto the manifold, and maintainability is poor. Incorporating the selector valve and the plurality of shuttle valves into a single common body makes them well organized but tends to result in inconvenience on the contrary in individually checking operations of the selector valve and the OR circuit or in individually exchanging or maintaining them.
It is a technical object of the present invention to incorporate a selector valve for switching working fluid and an OR circuit portion which is a combination of a plurality of shuttle valves into individual casings so as to form the selector valve and the OR circuit portion in forms independent of each other, thereby enhancing ease of handling of them and allowing individual operation checks and exchanges to enhance maintainability.
To achieve the above object, according to the invention, there is provided an interlock valve comprising: a main valve portion including a plurality of valve ports, a valve hole with which the valve ports communicate, a main valve portion having a valve member housed to be displaced in the valve hole to select a flow path; a driving-side operating portion having a driving piston disposed on a side of one end of the valve member to operate by an action of fluid pressure to switch the valve member and a driving pressure chamber for causing the fluid pressure to act on the driving piston; a return-side operating portion having a return spring disposed on a side of the other end of the valve member; and an OR circuit portion formed of a plurality of shuttle valves, a plurality of OR input ports, and one OR output port such that fluid pressure input to any one of the OR input ports is output from the OR output port to the driving pressure chamber, wherein the main valve portion is provided in a first casing, the OR circuit portion is provided in a second casing, the driving-side operating portion is provided in a first end plate, the return-side operating portion is provided in a second end plate, the first casing and the second casing arranged side by side are sandwiched between the first end plate and the second end plate disposed to face each other, and a flow path connecting the OR output port and the driving pressure chamber is provided in the first end plate.
In the interlock valve having the above structure, if fluid pressure is input to one of the OR input ports, the fluid pressure is output from the OR output port to the driving pressure chamber and pushes the driving piston to move the valve member. Therefore, the flow path for the working fluid is selected. At this time, the return spring is compressed and energy is stored. If input of the fluid pressure from the OR input port ceases, the valve member and the driving piston are returned to a home position by a biasing force of the return spring to select an original flow path.
Because the main valve portion and the OR circuit portion are incorporated into individual casings to be formed in forms independent of each other and the casings arranged side by side are sandwiched between the first end plate and the second end plate having the driving side operating portion and the return side operating portion, the whole valve can be formed in a systematic, compact, and organized form and can be easily handled in assembly. Moreover, because a check of operations and exchange in a case of a failure of the main valve portion and the OR circuit portion can be carried out individually, maintainability is excellent.
In the invention, it is preferable that the return-side operating portion provided in the second end plate has a return piston for forcibly returning the valve member and a return pressure chamber for causing fluid pressure to act on the return piston, that the return spring acts on the valve member through the return piston, and that a return port is provided to the second casing and connected to the return pressure chamber.
As a result, by supplying the fluid pressure from the return port to the return pressure chamber in an emergency, the valve member can be returned forcibly by the return piston and the biasing force of the return spring.
According to another preferable structural form of the invention, the first end plate has an operation indicator to be brought into an indicating state by an action of fluid pressure and the operation indicator is connected to the OR output port and the driving pressure chamber.
The operation indicator has a transparent cover provided to the first end plate to project outside and an indicating element colored with a prominent color, disposed for forward and rearward movements inside the transparent cover, and biased elastically and rearward by a spring, a piston portion is provided to a lower end portion of the indicating element and is housed for sliding in an indicating pressure chamber, and the indicating pressure chamber communicates with the driving pressure chamber.
According to a concrete structural form of the invention, the OR circuit portion has first to third three shuttle valves and first to fourth four OR input ports, two input ports of the first shuttle valve are connected to the first and second OR input ports, two input ports of the second shuttle valve are connected to the third and fourth OR input ports, output ports of the first and second shuttle valves are respectively connected to two input ports of the third shuttle valve, and an output port of the third shuttle valve is connected to the OR output port.
In the valve of the invention, the respective valve ports of the main valve portion open in a lower face of the first casing, the respective OR input ports of the OR circuit portion open in a lower face of the second casing, and the first casing and the second casing are mounted onto a common manifold such that fluid pressure is supplied to and discharged from the respective ports through the manifold.